Process for obtaining metals having a high melting point, such as tungsten



march 1?. wzs. I 1,529,943

A. C. C. M. P. BRUNO? DE ROUVRE PROCESS FOR OBTAINING METALS HAVING A HIGH MELTING POINT,

SUCH AS TUNGSTEN Filed March '7, 1923 for the purification Eatented l'tllar. 17, 1925..

ANTOINE CHARLES CONSTANTIN MARIE PHILIPPE BRUNOT DE ROUVRE, OE PARIS, FRANCE, ASSIGNO'R TO SOCIETE ANONYIYEE IDES BREVETS IBERTHET, 0F PARIS,

FRANCE.

PROCESS FOR OBTAINING METALS HAVING A HIGH MELTING- E'OINT, SUCH AS TUNGSTEN.

Applicationfiled March 7, 1923. Serial No. 623,514.

To (LZZ whom it may concern:

Be it known that I, AN'roiNn Gunners CoNs'mN'rm Mann-1 Pniurrn BRUNOT on Rooms, Ll l'lue Drouot, Paris, France, have invented Process for Obtaining Metals Having a- High lvlelting Point, Such as Tungsten, of which the following is a full, clear, and exact description.

This invention relates to a process for. obtaining metals having a. high-melting point; it applies more particularly to tungsten and molybdenum. It allows of obtaining these metals by fusion, thus imparting to them special qualities; more particularly the tungsten obtained by this new process forms a. new product which differs much from the tungsten which is manufactured according to the known method.

Up to now, it has been impossible to obtain molten tungsten because if a carbon crucible is used, tungsten carbide is formed and if other substances are used for making the crucible, the latter is destroyed before the tungsten melts.

The process which is the object of the present invention does away with these two serious drawbacks. It consists'essentially in causing an electric arc to strike in a gaseous medium, between two electrodes made of tungsten (for instance) and in causing tungsten powder to fall gradually upon the crater of the are (or even upon one only, which will preferably be the positive crater when the are is fed by a direct current). When the current of the electric arc is adjusted in a suitable manner, the crater of the electrodes melts superficially and the tungsten powder melts gradually according as it falls upon this crater; by continuing with this operation, the volume of the electrode is little by little increased by a deposit of molten tungsten. Hydrogen is suitable as the surrounding gas in this case; however, hydrogen may used with a nitrogen and with another gas having the same properties.

The use of several gases may be necessary of the tungsten because the powder which is found in the trade often contains foreign substances.

Instead of metallic powder, an oxygenated compound of the metal (for instance,

be simultaneously tungstic acid) may be used, when the surrounding gas contains hydrogen.

An apparatus enabling the carrying of the process according to the present invention into e li'ect, will be hereinafter described, by way of example. With reference to the accompanying drawing, in which the figureis a diagram of the appa atus,

This apparatus comprises two vertical electrodes .6- and Z); the upper electrode 7) is pierced by a small axial channel 0 through which passes the powder to be melted. A distributor, consisting for instance of a small. Archimedean .screw (Z, takes the tungsten powder into a receptacle 6 provided to this end and brings it above the orifice of the channel of the upper electrode; this powder falls little by little upon the crater of the lower electrode (1. and melts as it has been explained above. In order to ensure a complete and regular fusion upon the entire surface of the lower electrode, the latter may be displaced in a horizontal plane; in this manner the arc may be successively brought upon all the points of the electrode.

According as the tungsten increases the length of the lower electrode, the latter is moved away in such. a manner that the are shall always have the desired length. All these arrangcn'ients may be rendered auto matic by means of an electric or mechanical drive which is easy to establish, such. as a small motor f, causing the rotations by means of a tangent screw g of the lower electrode and actuating by means of a relay lz, an arrangement intended to move the electrodes apart and to proportion the delivery of the powder to the speed of fusion.

The tungsten powder may also be brougl'it to the arc by means which are independent of the electric circuit; in this case the arc may be struck by means of any known arrangement of electrodes.

When a. molten mass has been obtained, the latter is subjected to a hammering which imparts to it a shape suitable for the purpose for which it is intended, permitting for instance its passing through drawing plates for the purpose of obtaining filaments for electric arcs. The hammering and the wire drawing may be carried out with heat in an indifferent or reducing medium. These filaments may be advantageously used in electric vacuum or gas lamps and give better results than the filaments which have been hitherto used.

It is also possible to hammer and to roll the ingot for obtaining plates.

Owing to the qualities obtained by fusion, the tungsten thus obtained can be much more easily Worked than the tungsten worked by the known methods.

Claims:

1. A process for obtaining by melting metals having a very high melting point, such as tungsten, WlllCll consists: in gradu ally pouring, in a pulverulent condition, the metal to be melted in the crater of an electric arc struck, in a non-oxydizing atmosphere, between two electrodes made of metal the melting point of which is equal or superior to that ol the metallic powder to be melted, in regulating the fall of the said metallic powder in such a manner that the latter melts in proportion to its arrival in the crater of the electric arc and becomes soldered to the electrode presenting this crater and that this electrode thus increases progressively in size by the successive de posits of molten metal, and in constantly regulating the spacing apart of the electrodes in proportion to the deposits of molten metal so that the electric arc may always have the same length.

2. A process for the manufacture of small sticks of molten tungsten which consists: in gradually pouring tungsten powder in the crater of an electric arc struck in a nonoxydizing atmosphere, between two electrodes made of tungsten, in regulating the fall of this tungsten powder sothat the latter melts in proportion to its arrival in the crater oi": the electric arc and becomes soldered to the electrode presenting this crater, and that this electrode thus increases progressively in size by the successive deposits of molten metal, and in constantly regulating the spacing apart of the elec trodes in proportion to the said deposits so that the electric arc may always have the same length.

3. A process for obtaining by melting metal having a very high melting point, such as tungsten, which consists; in gradually pouring, in a pulverulcnt condition, the metal to be melted in the craters of electric arcs struck between several electrodes made of a metal the melting point of which is equal or superior to that of the metallic powder to be melted, in regulating the fall oi the said metallic powder in such a manner that the latter melts in proportion to its arrival in the craters of the electric arcs and becomes soldered to the electrodes presenting these craters, and that these electrodes thus increase progressively in size by the successive deposits of molten metal, and

in constantly regulating the spacing apart of? the electrodes in proportion to the said deposits so that the electric arcs may always have the required length.

The foregoing specification of my Process for obtaining metals having a high melting point, such as tungsten signed by me this 23d day of February 1923.

ANTOENE CHARLES CONSTANTIN MARlE PHlLlPPE BRUNOT DE ROUVRE. 

